In a conventional fastener driving tool, a fastener such as a nail is adapted to be driven into a workpiece such as a wood and a gypsum plaster board by urging and accelerating a plunger using an urging force of a spring. Such fastener driving tool accumulates an resilient energy of the spring by a motor accommodated in the fastener driving tool.
A coil spring can accumulate an resilient energy by expansion or compression. The expansion or compression of the coil spring is achieved by a motor, a reduction gear, a plunger and a plurality of rotation gears as described in Japanese Patent Publication No. H09-295283. Each of the plurality of the rotation gears has a driving pin that is fixed at a position separately from a rotation center of each rotation gear. The plunger has a plurality of protrusions. The plunger is pushed up in a prescribed stroke by engagement between the driving pins and the plurality of protrusions. With this structure, one rotation gear can push up the plunger in expansion or compression stroke of the spring that is equal to a diameter of the rotation gear. Thus, if the prescribed stroke of the plunger is increased, expansion or compression stroke of the spring must be increased. Thus, the diameter of the rotation gear or the number of the rotation gears must be increased.